Non-alcoholic to metabolic associated fatty liver disease: Cardiovascular implications of a change in terminology in patients living with HIV

Background and Aims: It has recently been suggested that the definition of non-alcoholic fatty liver disease (NAFLD) be changed to Metabolic Associated FLD (MAFLD) to better reflect the complex metabolic aspects of this syndrome. We compared the ability of MAFLD and NAFLD to correctly identify high CV risk patients, sub-clinical atherosclerosis or a history of prior CV events (CVEs) in patients living with HIV (PWH). Methods: Single center, cross-sectional study of PWH on stable anti-retrovirals. NAFLD was diagnosed by transient liver elastography; published criteria were used to diagnose MAFLD (JHepatol.2020;73(1):202-209). Four mutually exclusive groups were considered: low (<7.5%) vs high (>7.5%) ASCVD risk, subclinical CVD (carotid IMT ≥1 mm and/or coronary calcium score >100), and prior CVEs. The association of NAFLD and MAFLD with the CVD risk groups was explored via a multinominal model adjusted for age, sex, liver fibrosis, HIV duration, nadir CD4 and current CD4 cell count. Results: We included 1249 PWH (mean age 55 years, 74% men, median HIV duration 24 years). Prevalence of overweight/obesity and diabetes was 40% and 18%. Prevalence of NAFLD and MAFLD and overlapping groups are shown in Fig 1A. Fig 1B shows distribution of NAFLD/MAFLD in the 4 patient categories (p-for-trend <0.001). Both MAFLD and NAFLD were significantly associated with an increased risk of CVD compared to the reference level (ASCVD<7.5%) (all p-values <0.004; Fig 2). Conclusions: NAFLD and MAFLD perform equally in detecting CVD or its risk. The proposed change in terminology may not help to identify PWH requiring enhanced surveillance and preventative interventions for cardiovascular disease

Mechanisms of Intramolecular Communication in a Hyperthermophilic Acylaminoacyl Peptidase: A Molecular Dynamics Investigation

Protein dynamics and the underlying networks of intramolecular interactions and communicating residues within the three-dimensional (3D) structure are known to influence protein function and stability, as well as to modulate conformational changes and allostery. Acylaminoacyl peptidase (AAP) subfamily of enzymes belongs to a unique class of serine proteases, the prolyl oligopeptidase (POP) family, which has not been thoroughly investigated yet. POPs have a characteristic multidomain three-dimensional architecture with the active site at the interface of the C-terminal catalytic domain and a β-propeller domain, whose N-terminal region acts as a bridge to the hydrolase domain. In the present contribution, protein dynamics signatures of a hyperthermophilic acylaminoacyl peptidase (AAP) of the prolyl oligopeptidase (POP) family, as well as of a deletion variant and alanine mutants (I12A, V13A, V16A, L19A, I20A) are reported. In particular, we aimed at identifying crucial residues for long range communications to the catalytic site or promoting the conformational changes to switch from closed to open ApAAP conformations. Our investigation shows that the N-terminal α1-helix mediates structural intramolecular communication to the catalytic site, concurring to the maintenance of a proper functional architecture of the catalytic triad. Main determinants of the effects induced by α1-helix are a subset of hydrophobic residues (V16, L19 and I20). Moreover, a subset of residues characterized by relevant interaction networks or coupled motions have been identified, which are likely to modulate the conformational properties at the interdomain interface

Simulations of ApAAP in open conformation.

<p>A) The cross-correlated motions at the interdomain interface (correlation threshold of 0.4) in simulations of open ApAAP are shown as green lines (positive correlations) and blue lines (negative correlations). The β-propeller and the catalytic domains are shown in pale-green and white, respectively, whereas the α1-helix is highlighted in pale-cyan. D376, which is the hinge residue proposed for the opening of the catalytic cleft <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0035686#pone.0035686-Harmat1" target="_blank">[33]</a> is shown. B) The salt bridge networks at the interface between the β-propeller and the catalytic domains in ApAAP open conformations are shown as spheres connected by yellow/green lines according to their persistence. The β-propeller domain and the catalytic domain are highlighted in pale-green and white, respectively, whereas the α1-helix in pale-cyan. Catalytic residues are shown as sticks.</p

The shortest communication paths from the hydrophobic residues of the α1-helix to the catalytic site.

<p>The shortest and highest frequency pathways, as detected by PSN-DCCM analysis, between V16 (A), L19 (A), I20 (B) and the catalytic H556 and D524 are shown as sticks proportional to the intensity of the correlation.</p

α1 deletion perturbs the architecture of ApAAP active site.

<p>A–F) Local network of salt bridge interactions mediated by R526 in the wild type ApAAP (A), ApAAP-Δ21 (B), ApAAP-I12A (C), ApAAP-V13A (D), ApAAP-V16A or ApAAP-I19 (E), ApAAP-L20A (F) are shown with different shade of color which are proportional to the persistence of the interaction during dynamics (with the darker colors indicating an higher persistence). G) wild type ApAAP and ApAAP-Δ21 average structures from the simulations are shown in white and blue, respectively. The catalytic residues are indicated by sticks. H–I) Coupled motions of the catalytic triad. The coupled motions which involve the catalytic triad are shown for wild type ApAAP (red sticks, H) and ApAAP-Δ21 (green sticks, I). Catalytic residues are shown as sticks and the α1-helix highlighted in cyan.</p

Salt bridge interactions at the interface between the two protein domains in ApAAP-Δ21.

<p>The salt bridge pairs are indicated by lines and the residues involved in the salt bridges and their networks as spheres. The catalytic residues are shown as sticks and the β-propeller and catalytic domain colored in marine and magenta, respectively. The salt bridges are connected by lines of different shade of colors according to their persistence in the MD ensemble (from green to blue for increasing persistence values).</p

Protein dynamics fingerprint for wt, Δ21, and mutants ApAAP variants.

<p>The projections of the displacement described by the first principal component on the 3D structure are shown for wt (A), Δ21 (B), I12A (C), V13A (D), V16A (E), L19A (F), and I20A (G) ApAAP variants with the different simulation frames colored with different shade of colors from light cyan to purple. The catalytic triad and the α1-helix are shown as spheres and cartoon, respectively. The analyses were also carried out for the second and third components, which provide the same general view and are therefore not presented here.</p

Salt bridge clusters in wild type ApAAP.

<p>Salt bridges belonging to cluster 1 (A, blue), cluster 2 (B, E, cyan) and clusters 3 (B, yellow) and 4 (B, green) are shown as spheres and connected by sticks. C–D) Details on salt bridges belonging to cluster 1 and located in proximity of the catalytic site. E) Details of some salt bridge networks located in cluster 2. The α1-helix is highlighted as cyan cartoon. The sticks connecting the salt bridges are colored according to the persistence of the interactions in the simulations (from light to dark magenta for increasing persistence values).</p

Summary of the multi-replica all-atom MD simulations.

<p>Summary of the multi-replica all-atom MD simulations.</p